I am trying to use matlab to find the roots of a quadratic by the standard iterative techniques. I am totally on top of all this work in theory and in practice when it comes to doing it with a calculator or Excel, but I have never used matlab before and I have been given the code below to use.(adsbygoogle = window.adsbygoogle || []).push({});

The trouble is I don't know how I am s'posed to enter the equation that I am using for the iteration.

Suppose the equation was x^2 - 4x -11 = 0

Then I obviously need to get the computer to recognise that I want to find the fixed point of

x = (4x+11)^.5

But where do I tell the computer that this is the equation I want to solve?

Here is the code I was given. I suppose it must have something to do with "Gather input data"?

% programme Bisection

% Bisection method for finding root of equation

% Algorithm from Burden & Faires page 47

%

% Gather input data

a = input('Input lower endpoint: ');

b = input('Input upper endpoint: ');

tol = input('Input tolerance: ');

Nmax = input('Input maximum number of iterations: ');

count = 1;

fa = f(a);

% Iterate

while count <= Nmax

p = a + (b-a)/2;

fp = f(p);

% Test for finish

if or(fp == 0, (b-a)/2 < tol)

disp('Calculated root is: ');

disp(p);

disp('Number of iterations was: ');

disp(count);

return;

end

count = count + 1;

% Compute next interval

if fa*fp > 0

a = p;

fa = fp;

else

b=p;

end

end

% If we get here then no root was found

disp('Method failed: Number of iterations: ')

disp(count);

Thankyou very much in advance.

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# Using matlab to find roots.

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